Scientist for a Day

Samiha Rahman

Target: Titan

"Searching for alien life is one of the fundamental inspirations for cosmic exploration. Therefore, I think Saturn’s largest moon Titan is the most suitable candidate for further observations.

From the results of the Cassini-Huygens mission, Titan has similar external features to Earth with an abundance of organic molecules. Carbon, hydrogen and nitrogen-rich Titan has a surface temperature of nearly negative 180°C. Even though low temperatures and lack of liquid water proposes a case against developing stereotypical life, lakes of liquid methane and ethane with earth-like clouds and rains have the potential to be the most likely place for life in the solar system.

Visiting Titan again should be a priority because of similar characteristics to theorized primordial earth, which gained Titan the reputation of a test case. Additionally, Titan is chemically and geologically much more active than other celestial bodies. Some believe these feature to be prerequisite for the development of life.

The 2015 research paper at Cornell University suggested an "azotosome" or nitrogen-based membrane suitable to live on Titan. The membrane consists of nitrogen, carbon and hydrogen molecules which are available on Titan. This nitrogen-based membrane has similar stability and flexibility to a typical terrestrial phospholipid. It marks a new horizon for the possibilities in formation of life.

Voyager's observations have shown photochemical processes occur in the upper atmosphere of Titan, creating rich gas of hydrocarbons, which can act as a potential source of chemical energy. Based on the suggestion that methane-based life is widespread due to the presence of methane almost everywhere on Titan, astrobiologists Chris McKay and Heather Smith predicted that there would be a depletion of acetylene, ethane, and hydrogen in the troposphere of Titan in a research paper published in 2005. The observation of upper and lower atmosphere of Titan by researchers from the Johns Hopkins University further supported this prediction. This may be the result of life on Titan using hydrogenation for energy and creating acetylene as waste. It is also speculated that below freezing temperature can result in an extremely slow metabolism. This type of slow mechanism is observed in creatures living in freezing conditions on Earth.

Titan’s surface is formed with ice landscapes. It is speculated that life on Titan may have a special enzyme for collecting oxygen from the ice to make the basic building blocks of life. Cassini’s data shows water oceans beneath the surface. But having dense phosphorus, potassium, and sulfur salt does slim the possibility of life in the oceans.

In most research and studies, the importance of water is emphasized as a factor for finding life. But the liquid nourished Titan provides a rare condition that challenges our idea of life. Further exploration can not only provide knowledge about the mechanism and conditions on Titan but also broaden our knowledge about ourselves as a living being. And as such, we should undertake further missions to Titan, in that it could help us solve one of the fundamental mysteries in the history of science."